The invention relates to a contact which utilizes insulation displacement technology. In particular, the invention is directed to the use of insulation displacement technology with fine wires.
The use of insulation displacement contacts (IDC) technology is well known in the electrical connector industry. In general, a slot is provided in a contact which cooperates and terminates a respective wire. As the wire is moved into engagement with the slot, the edges of the slot cut through the insulation provided on the wire. The width of the slot is less than the width of the conducting core of the conductors so that as the conductor moves into the slot the edges of the slot contact the conductor to form the electrical contact therebetween.
Terminals of this type are well known in the industry and are widely used for wires having diameter of at least 0.33 millimeters (which is the equivalent of an AWG 28 WIRE), but they are not used to any significant extent for wires having a diameter of less than 0.33 millimeters. The reason that insulation displacement technology is not used for fine wires is that it is impractical to produce terminals having extremely narrow slots. Consequently, as narrow slots are difficult to produce, the electrical connection between the terminals and fine wires is not assured. For example, the slot required for a wire having a diameter of about 0.2 millimeters must have a width of about 0.1 millimeter. Utilizing conventional die and punch technology, this size slot is extremely difficult to manufacture.
The wire-receiving slots are produced in the sheet metal from which the terminals are manufactured by means of conventional punch and die techniques. In other words, a punch is provided having a width equal to the width of the slot and a die is provided having an opening into which the punch moves. The sheet metal is supported on the die; and when the punch moves into the die, the slot is formed. As a practical matter, it is not possible to produce slots in sheet metal of a given thickness which have a width which is significantly less than the thickness of the sheet metal. In particular, a slot having a width which is less than half the thickness of the stock material is difficult to manufacture. Consequently, if the stock metal has a thickness of about 0.30 millimeters, it is impractical to punch a slot in the stock metal having a width which is 0.15 millimeters. If a wire has a diameter of 0.20 millimeters, the slot width should be approximately 0.10 millimeters. As previously stated, a slot having this width cannot be produced in stock metal having a thickness of 0.30 millimeters. This limitation on slot width exists because the narrow punch will break because of the extremely high stresses imposed on the punch when it moves against the stock metal. Alternatively, if the punch does not break, the high wear on the punch and the die will cause the edge of the slot to be deformed, thereby providing ineffective electrical connection between the conducting core of the wire and the electrical terminal.
It might appear that the terminals for extremely fine wires might be produced from extremely thin stock metal which would permit the formation of extremely narrow slots in the stock metal. However, if the stock metal used for the terminals is extremely thin, the resulting terminals will be flimsy and will be useless for that reason. In other words, if extremely thin stock is used, when the wire is moved into engagement with the slot, the thin metal sock will be deformed and the insulation of the conductor will not be displaced. As the insulation is not removed properly and as the width of the slot is not properly controlled, the conducting core of the wire will not be placed in electrical connection with the electrical terminal.
U.S. Pat. No. 4,600,259 discloses a contact for use with fine wire. The miniature electrical contacts are provided with closely-spaced thin plates which define there between lengthy passageways for receiving closely-spaced conductors of a wire or cable. Zones around the contact surface sections are coined to reduce their thickness such that the contact surface sections will engage and terminate the wire. This allows fine wires to be terminated such that the conducting cores are provided in electrical engagement with the electrical contacts.
The present invention is directed to the achievement of an approved terminal which is relatively inexpensive to manufacture and which provides the required integrity of the electrical contact to insure that an electrical connection will be made between the core conductors of the fine wire and the electrical contact. The electrical contact of the present invention is stamped and formed using conventional stamping technology and is then folded over to provide a slot with the width appropriate to terminate fine wires.
The invention is directed to an electrical contact for terminating fine wires thereto. In other words, the invention is directed to an electrical contact in which the thickness of the stock material is greater than the width of an insulation displacement slot provided therein. The contact is manufactured utilizing conventional stamping and forming operations to create an insulation displacement slot which could not be previously manufactured using these techniques. Consequently, the invention eliminates the need to manufacture narrow slots by means of lasers and the like
In particular the invention is directed to an electrical contact for terminating fine wire. The contact has a wire receiving section and a mounting section integrally attached to the wire receiving section. An insulation displacement plate is provided on the wire receiving section, the insulation displacement plate has a first portion and a second portion which are positioned proximate each other to form the insulation displacement plate. A locking member is provided on the first portion and cooperates with the second portion to maintain a first portion edge of the first portion adjacent to a second portion edge of the second portion. A first slot portion stamped from the first portion edge and a second slot portion stamped from the second portion edge are positioned to form an insulation displacement slot, whereby the width of the insulation displacement slot can be dimensioned to receive and terminate the fine wires therein.
Curved bight portions are integrally attached to either end of the insulation displacement plates and the strain relief plates. The bight portions connect the plates together and maintain the spacing therebetween.
The invention is also directed to a method of manufacturing the electrical contact to terminate fine wire. A blank of material is stamped using conventional punch and die techniques to provide a first slot portion at a first free end and a second slot portion at an oppositely facing second free end. A first portion with the first free end provided thereon and a second portion with the second free end thereon are then bent or formed such that the fist free end and the second free end are positioned adjacent each other. In this position, the first slot portion and the second slot portion cooperate to form an insulation displacement slot which has a width which is less than the thickness of the material. The punch and die used to make the first slot portion and the second slot portion have a width which is greater than the width of the insulation displacement slot made from the first slot portion and the second slot portion.